npm and error messages

node_modules/es5-ext/optional-chaining.js

@@ -0,0 +1,12 @@
+"use strict";
+
+var isValue = require("./object/is-value");
+
+var slice = Array.prototype.slice;
+
+// eslint-disable-next-line no-unused-vars
+module.exports = function (value, propertyName1 /*, …propertyNamen*/) {
+	var propertyNames = slice.call(arguments, 1), index = 0, length = propertyNames.length;
+	while (isValue(value) && index < length) value = value[propertyNames[index++]];
+	return index === length ? value : undefined;
+};